Device for separating liquid particles from a gas stream

ABSTRACT

A device for separating liquid particles from a gas stream including a filter insert ( 8, 9, 11 ) placed in a gas stream ( 3 ) generated by an external pressure difference. Liquid particles remain on the outer surface of the filter insert ( 8, 9, 11 ) on the raw gas side and form droplets which can flow down into a collecting chamber ( 6 ). The device is a compact separating module ( 1 ) with several stages, a cyclone ( 5 ), a filter insert ( 8, 9, 11 ) and a pressure regulating valve ( 12 ).

BACKGROUND OF THE INVENTION

The invention relates to a device for separating liquid particles from agas stream, in particular an oil vapor separator in accordance with thepreamble to the main claim.

The fact that such filter inserts are directed into the flow path of agas stream and get caught on the stationary structures of the filterinserts in the process, for example on the filaments of a non-wovenfabric and liquid droplets which trickle into a collection chamber andthen can be removed from there or can be redirected into a liquidcirculation system is known from GB 988 692, for example. It isimportant for many types of applications, such as for a device in thesuctioning tract of an internal combustion engine for a motor vehicle,that a higher degree of separation be attained at a lower loss ofpressure in the flow path, without the need for combining a large numberof additional aggregates in a manner that demands a great deal of space.

For example, that a pressure control valve is connected into asuctioning path is a known fact from DE-40 22 129 C2 (corresponding toU.S. Pat. No. 5,090,393). This pressure control valve is built into anair exhaust pipe between the engine crankcase and the suctioning pipe orthe air filter in a motor vehicle by means of two flanges, for example.

SUMMARY OF THE INVENTION

The basis of the task of the invention is to develop a device forseparating liquid particles from a gas stream in accordance with thepreamble to the main claim in a simple manner, such that a compactmodule can be constructed in which a high level of separation isreliably ensured under ideal pressure conditions. The inventive devicefor separating liquid particles from a gas steam, in particular as anoil vapor separator, solves the task assigned with the characteristicsindicated in the distinguishing features of the main claim.

The inventive device is particularly advantageous because a compactarrangement as well as a cyclone for the first crude separation ofliquid particles and a subsequent filter insert for other, finer levelsof separation in connection with a pressure control valve, which islocated directly on the filter insert in a universal housing and whichensures an ideal rate of flow of the gas stream in a structurally simplemanner.

In order to separate the liquid particles as completely as possible, itis important that the rate of flow of the gas particularly correspondwith the permeability conditions of the filter inserts so that theliquid condensation form are not entrained once again via an overly-highrate of streaming gas. The size of the droplets forming also plays arole in relation with the fiber structure of the filter insert in thisconnection.

The inventive device is particularly advantageous in accordance with anembodiment of a sub-claim with a multi-layered filter insert. A crudeseparation and a fine separation can be undertaken in this connectionwith different layers of the filter insert, for example with arelatively narrow fiber structure and a relatively coarse fiberstructure. The fine-tuning of the rate of flow necessary for this isfeasible in a simple manner by means of the pressure control valve whichis located immediately thereafter in the direction of flow. The rate offlow is accordingly optimized such that droplets of a certain size,determined by the fiber structure, are no longer entrained into the gasstream, as a result of which the separation effect would be diminished.

Other advantageous embodiments are stated in the other sub-claims.

BRIEF DESCRIPTION OF THE DRAWING

An embodiment of the inventive device for separating liquid particlesfrom a gas stream is explained using the illustration. The FIGURE in theillustration shows a cross-section through a module wit h a multi-stageseparation of the liquid particles.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A separating module 1 is shown in the FIGURE in which the gas, which isindicated by arrows 3, enters the separating module through a raw gasinlet 2. A first cyclone, which is formed by a cylinder 5 located in theinterior and which sets the incoming gas in rotation via a guide deviceor the like, is located in a first cylinder 4. The liquid particles areaccelerated radially via the rotation and then flow away from the sidewalls of the cylinder 4 into a collection chamber 6.

The collection chamber 6, depicted here schematically, is connected to aliquid outlet 7 in the lower area of the module 1. The liquid outlet 7is embodied as a siphon-like drain, not shown in more detail here, sothat interfering gas suctioning does not ensue in the separation module1.

The gas purified in the first stage described above enters a secondcylinder 10 onto layers 8 and 9 of the filter insert, each of which areheld on a gas-permeable support body 11. Liquid droplets, which areseparated from the gas stream (arrow 3) and which also are deposited inthe collection chamber 6, likewise form in these separating layers,which are made of varying fibrous structures.

The pure gas, which has now been essentially liberated of liquidparticles, is guided in cylinder 10 into the pressure control valve 12located above. The pressure control valve 12, not explained in moredetail here, is specified in the prior art mentioned above in U.S. Pat.No. 5,090,393, which is expressly incorporated by reference herein, andhas the task of ensuring a relatively constant pressure and,accordingly, a constant rate of flow in the interior of the separatingmodule 1, even in the event of large vacillations of the pressureexerted from the exterior. The pure gas (arrow 3) hereby enters theupper area 13 of the pressure control valve 12 and leaves the separatingmodule 1 via the pure gas outlet 14.

What is claimed is:
 1. A compact apparatus for separating liquidparticles from a gas stream produced by an external pressure difference,said apparatus comprising a multi-stage separating module comprising araw gas inlet, first and second separating stages, a collecting chamberfor collecting liquid separated from the gas stream by said first andsecond separating stages, and a clean gas outlet; said first separatingstage being arranged under said raw gas inlet and comprising a cyclonedisposed in the gas stream for separating liquid particles by rotationalacceleration; said second separating stage being disposed laterallyadjacent said first separating stage and comprising a cylindrical filterinsert disposed in a cylindrical housing such that substantially itsentire radially outer surface can be contacted by the gas stream, saidfilter insert comprising concentric first and second annular separatinglayers each being supported on a respective annularly internal gaspermeable support body; and said apparatus further comprising a pressureresponsive gas flow regulating valve disposed directly above the filterinsert between the filter insert and the clean gas outlet of theseparating module, said pressure responsive gas flow regulating valveensuring a substantially constant pressure in the separation module anda substantially constant rate of gas flow through the separation moduledespite variations in the external pressure difference.
 2. An apparatusaccording to claim 1, wherein said first and second separating stagescomprise first and second hollow cylinders connected to each other atthe bottom, wherein the cyclone of said first separating stage isarranged in the first hollow cylinder such that liquid particlesseparated from the gas stream by rotational acceleration impinge upon aninternal wall of the first cylinder and run down said first wall to thecollecting chamber; and wherein the second hollow cylinder forms thecylindrical housing of the second separating stage, and the filterinsert of said second separating stage is arranged in the secondcylinder such that liquid particles remaining in the gas stream afterthe first separation stage impinge upon the separating layers of thefilter insert and run down the separating layers to the collectingchamber.
 3. An apparatus according to claim 1, wherein the first andsecond separating layers of said filter insert comprise fibrous textilelayers, and the gas permeable support bodies are hollow cylindricalbodies.
 4. In an internal combustion engine having an air intake tract,the improvement comprising an apparatus according to claim 1, arrangedin the air intake tract to separate oil particles from air sucked inthrough the air intake tract.